The compositions, articles, and methods disclosed herein have applications in many fields, such as hard coats. This disclosure focuses on applications on the ophthalmic field. More specifically, this disclosure focuses on methods of producing UV curable high refractive index (RI), clear, low-haze, coatings.
Hybrid epoxy-acrylic coatings provide good mechanical and optical properties. Such hybrid formulations are used in optical coating applications, especially in UV-cured coatings for plastic ophthalmic lenses.
Due to its unique, high refractive index (RI) and other mechanical properties, such as hardness and durability, zirconium dioxide (ZrO2) nanoparticulate has been investigated for use in protective coatings, and especially optical coatings.
Zirconium dioxide has successively been dispersed in acrylic monomers or in epoxy monomers. For example, ZrO2 colloids can be dispersed in either acrylic or epoxy monomers where the ZrO2 nanoparticle surface is first functionalized, such as with silane compounds. Dispersed ZrO2 colloid in either acrylic or epoxy monomers can provide stable, clear fluids, capable of application to a surface, as a coating.
It has been believed that a colloidal dispersion of ZrO2 in a mixture of acrylic and epoxy monomers together would provide better optical and mechanical coating properties for applications such as plastic lenses. However, an acrylic ZrO2 colloid and an epoxy ZrO2 colloid have not been successfully mixed together for coating applications. The mixture becomes opaque or gels (making it unsuitable for application as a coating). No satisfactory solutions exist for ZrO2 colloids dispersed in a hybrid of epoxy-acrylic system.
Therefore, there is a need for a composition, and method of making a composition, comprising a high-index, ZrO2 nanoparticle colloid coating solution in an epoxy-acrylic hybrid system for UV curable coating applications.